Teun Remmers

Relationship between PA and the development of BMI in children | 25 Table 2: Associations between physical activity (PA) level and change in BMI z-scores between age 4-5 and 8-9 years, stratified for baseline weight status. Physical activity level Total PA beta (95% CI) Light PA beta (95% CI) MVPA beta (95% CI) Boys and girls ‡ Leaner ( n =145) Unadjusted -0.02 (-0.07 to 0.03) -0.03 (-0.09 to 0.02) 0.03 (-0.09 to 0.14)† Adjusted -0.01 (-0.06 to 0.04) -0.03 (-0.08 to 0.02) 0.04 (-0.07 to 0.15) Normal-weight ( n =286) Unadjusted 0.02 (-0.01 to 0.06) 0.05 (0.002 to 0.09) -0.04 (-0.11 to 0.03) Adjusted 0.01 (-0.03 to 0.05) 0.03 (-0.01 to 0.07) -0.05 (-0.13 to 0.02) Heavier ( n =144) Unadjusted -0.04 (-0.09 to 0.00)† -0.03 (-0.08 to 0.03)† -0.13 (-0.26 to -0.01) Adjusted -0.06 (-0.11 to -0.02) † -0.05 (-0.11 to 0.004)† -0.16 (-0.27 to -0.04) Boys Leaner ( n = 74) Unadjusted -0.02 (-0.09 to 0.05) -0.04 (-0.12 to 0.03) 0.05 (-0.13 to 0.23)† Adjusted 0.00 (-0.06 to 0.06) -0.03 (-0.09 to 0.04) 0.12 (-0.06 to 0.31) Normal-weight ( n = 146) Unadjusted -0.01 (-0.08 to 0.06) 0.03 (-0.04 to 0.10) -0.11 (-0.22 to -0.01) Adjusted -0.01 (-0.08 to 0.06) 0.03 (-0.05 to 0.10) -0.13 (-0.24 to -0.02) Heavier ( n = 63) Unadjusted -0.10 (-0.17 to -0.02) † -0.10 (-0.19 to -0.01) † -0.17 (-0.36 to 0.01) Adjusted -0.11 (-0.18 to -0.04) † -0.13 (-0.23 to -0.04) † -0.17 (-0.33 to -0.004) Girls Leaner ( n = 71) Unadjusted -0.01 (-0.07 to 0.04) -0.02 (-0.10 to 0.05) -0.00 (-0.14 to 0.13)† Adjusted -0.01 (-0.08 to 0.06) -0.02 (-0.11 to 0.07) 0.02 (-0.12 to 0.16) Normal-weight ( n = 140) Unadjusted 0.05 (0.004 to 0.09) 0.07 (0.01 to 0.12) 0.04 (-0.05 to 0.13) Adjusted 0.04 (-0.01 to 0.08) 0.04 (-0.01 to 0.10) 0.06 (-0.04 to 0.16) Heavier ( n = 81) Unadjusted -0.01 (-0.06 to 0.04)† 0.01 (-0.05 to 0.07)† -0.10 (-0.24 to 0.04) Adjusted -0.01 (-0.05 to 0.05)† 0.03 (-0.05 to 0.10)† -0.14 (-0.27 to -0.01) Regression coefficients (beta) represent the change in BMI z-scores per year for an absolute increment of 5% of physical activity (PA). Results of Generalized Estimations Equations linear regression with PA measured at age 4- 5 years and 6-7 years, and BMI z-score (standardized for age and sex) measured at age 4-5 years, 6-7 years and 8-9 years, using an exchangeable correlation structure to account for the repeated measurements. Since 105 participants were measured at both periods, this table represents the number of measurements instead of participants. Unadjusted models: only PA and time (age period) in the model; adjusted models: adjusting for origin of BMI z-score, bicycling, swimming, season, recruitment group, paternal- and maternal BMI. Weight status was categorized at the first measurement of BMI available at age 4-5 or 6-7 years (baseline), into leaner (lowest quartile), heavier (highest quartile) and normal-weight (middle two quartiles) children). Bold numbers indicate statistical significance of the regression coefficient at p < 0.05, †: gender interaction term was statistically significant at p < 0.05. ‡: Included an interaction term for gender x period in the adjusted models.